Centrifugal Clutch fits engines with a 3/4" crankshaft and running #40, #41 or #420 chain. Manufactured by Hilliard Sprocket has 10 Teeth for chain size #40, #41 and #420 Fits on 3/4" crankshaft Comes with 4 weights (shoes), "C" clips, bronze bushing and outer drum with sprocket #1041H